BMP2 cross-linked by transglutaminase 2 to collagen-plla scaffold promotes osteogenic differentiation in mesenchymal stem cells.

Transglutaminase 2 (TG2) was used to attach biologically-active BMP2 to collagen type I-coated poly-L-lactic acid (PLLA) nanofibrous scaffolds. Irreversibly cross-linked BMP2 retained its activity and induced Smad-dependent gene expression in cells seeded on PLLA-BMP2 scaffolds. These modified scaffolds promote osteogenic differentiation of human bone marrow-derived mesenchymal stem cells (hBMSCs) cultured in low-serum and growth factor free medium and support deposition of the calcified matrix and induction of the molecular osteogenic markers Runx2, osteopontin, osteonectin and bone sialoprotein. Importantly, the PLLA-BMP2 scaffolds did not support chondrogenic differentiation in hBMSCs as there was no expression of chondrogenic markers aggrecan, Sox 9, and collagen type II, and no deposition of cartilaginous glycosaminoglycan-rich matrix. Thus, TG2-mediated cross-linking of BMP2 to a scaffold is a novel approach to induce osteoblast-specific programming of hBMSCs in a spatially controlled manner.